Farsi font support in Oracle 10gR1

Hi all,
I have installed 10gR1 on win xp and now want to have "Farsi" (maybe you know it as persian) data.I don't need persian date,I only needs data that stored and showed in Farsi.On one of our server we could do that,I entered farsi data using EM client on same machine.NLS_LANG for both server and client was AMERICAN_AMERICA.WE8MSWIN1252.
But on another server we can't do that using exactly the same config for Oracle.It shows farsi data by strange symbols such as a reverse question mark.Do you know what is going wrong? Your help will be so appreciated.
PS:I have installed Farsi fonts for win for both systems.